Radio receiver tuning indicator



Jan. 22, 1952 G, BARRY RADIO RECEIVER TUNING INDICATOR Filed April 12, 1947 E N \6 wfo 2 ol 6 mmv@ m W w 2I\ H||| A 2 I Hmm 7./ .1| .H B l |l| www 6 v/ H H S |3| 9 l l 2 .l n w m IU 2, F 3, H H I 3 910| I; 3 .E I/f I. l www i1# 2M I l 2 Imwl 5 y. 4%. E o E Q/ 17. 6 2 6- fr M 3 H FlG.3

FIGA- INVENTOR. RALD J. BARRY ATTO R N E Patented Jan. 22, 1952 RADIO RECEIVER TUNING INDICATOR Gerald J; Barry, Fort Wayne, IInd.,'assignor, by mesne assignments, to Farnsworth Research Corporation, a corporation of Indiana Application April 1'2, 1947, ser'iaI Nn. 741,107

- 'fs claims. (01. 11s-124.1) i

This invention relates to tuning indicators for radio receivers and particularly to acompact illuminated tuning dial.

It is conventional practice to provide'A a radio receiver with a tuning indicator, the face .of

' reference is made to the following description,

which bears a scale indicative of the entire tuning I range of the receiver. Certain tuning indicators have tuning indicia in the form f a scale etched on a transparent indicator face which is arranged against a relatively lopaque or translucent background which, when illuminated, renders a pleasing effect. 'The observed effect is enhanced when the transparent indicator face is illuminated by edge lighting whereby' the etched tuning scale appears prominent on the indicator face. However, an indicator face, having a tuning scale etched thereon, is relatively costly due to the kexpense yof the etching process..

Tuning indicators are conventionally provided with a movable pointer whereby the tuning adjustment of the receiver may be indicated. The l movable pointer for a tuning scale which is arranged against a relatively opaque or translucent background, may comprise an intense beam of light which is projected, from behind, upon the background whereby the light beam penetrates therethrough and indicates to the operator the adjustment of the receiver tuning elements. Conventional mechanisms for providing the light beam pointer and moving it across the rear of the indicating face are relatively bulky and re quire a substantial amount of receiver spaceand, therefore, cannot normally be accommodated within the smaller type of receiver. y ,Y n

Accordingly, it is the primaryobject ofA this invention to provide an inexpensive tuning indcator having edge illumination.

A further object of the invention is to provide, in an edge lighted tuning indicator, a relatively small and compact luminous pointer mechanism,

movably arranged behind the scale face of the indicator and requiring a minimumof receive-r space for its movement.

In accordance with this 'inventionthere'is' provided a radio receiver tuning indicatorlcomprising rst and second transparent members disposed adjacent to one another. Tuning indicia are provided on the rear face of the first member which is disposed adjacent to front'face of the second member and a coating is provided on the rear face of the second member. A source of light may be arranged to project light along the adjacent and adjoining faces .of the` two members thereby to illuminate the tuning indicia.

For a better understanding of the invention,

together with other and further objects thereof,

taken in connection with the accompanying drawing, and its scope will be pointed out in the'l appended claims.

ln the accompanying drawing:

Fig. l is a front elevation of a radio receiver chassis including the tuning indicating means andthe receiver control means;

Fig. 2 is. an enlarged sectional view of the tuning. indicator taken on lines 2--2 of Fig. 1, and having a receiver cabinet added thereto;

Fig. 3 is a sectional view taken on lines .3-3

of'IEig. 1 showing the arrangement of the scale face members, the scale illuminating means, and the luminous pointer apparatus;

Fig. e is a sectional -view of the luminous pointer apparatus taken on lines 4-4 of Fig. 3; and

Fig. 5 is an enlarged sectional view of the tuning scale face members taken on lines 5-5 of Fig. 3.

Referring now to the drawing and particularly to Fig. l, there is provided, in accordance with this invention, a radio receiver including a chassis Ill which has a tuning indicator I I and a pair of'control knobs I2 and I3 which may be em'- ployed for wave-band switching and volume control purposes, asis conventional. For supporting the tuning indicator II, there is provided a pair of vertical supporting arms I4 and I5 which are suitably attached to the chassis l0. For indie eating the particular tuning adjustment of the receiver the indicator II is provided witha tuning scale bearingpane l1 having tuning' indicia 'I8 thereon. A beam of light I9 is projected thereon from the rear, the beam being adapted to move 'across the scale face I1 in correlated relationship with the adjustment of a tuning control knob 20. Inasmuch as receiver tuning elements are not to be considered a part of the present invention, they are not therefore described or illustrated herein.`

'The tuning scale pane I'I and a background member 22 are arranged in parallel relation and adjacent to each other and are mounted at each end on the frames 23 and 24. These frames 23 and 24 are affixed to the supporting arms I4 and I5 respectively. Edge lighting means in the form of lamps 25 and 25 are iixed to arms I4 and I5 as shown. It is to be noted, as shown in Fig. 3, that the edge lighting is not applied to the background member 22 but is restricted to the scale pane lIl by the frame member 23 which abuts the' edge of the background member 22 thereby to screen it from the light source.

Referring now to Fig. 5, there is shown an enlarged sectional view of the scale pane |1 and the background member 22. The scale pane I1 is a transparent material such as glass, or a suitable plastic material, and has arranged on the rear surface thereof the indicia I8 which, in one embodiment of the invention, comprises a suitable white paint, or like substance, which is applied by a conventional screening process. The background member 22 may also be of clear glass or plastic material and its front surface is arranged directly against the rear surface of the scale pane I1. Applied tothe rear surface of the background member 22 is a suitable translucent coating 21 which preferably is colored and which is almost impervious to the passage of light but which will convey therethrough a portion of an intense beam of light projected thereon.

A pair of rods or tracks 29 and 38 are arranged parallel to the tuning scale pane |1 and along its edges and are supported at-each end by the frames 23 and 24. There isV provided a carriage 3| slidably mounted ontracks 29 and 30 and having an upper guiding sleeve 32 and a. lower guiding sleeve 33. The guiding sleeves are xed to the carriage 3| and slidably engage the 'tracks 29 and 30 whereby the carriage may be moved laterally in either direction upon the tracks.

The` purpose of the carriage 3| is to support a light source for projecting the light beam I9 upon the rear surface of the background member 22 and reference is now had to Figs. 3 and 4 which are top and front sectional views of the carriage and associated light source. The c arriage 3| comprises a compartmented structure which is light shielded and contains therein a light source 36, a light reflecting prism 31, a vertical elongated aperture 38, a cylindrical lens 39 and a light shield 48.

The light source 36 may consist of a conven tional dial light bulb, or the like, and is shown in Fig. 4 slidably mounted, for focusing purposes, to the light shield 48. There is also shown connected to the light source 36 a cable 49 which is passed through an aperture 58 in carriage 3| for connection to a power source.

The light shield 40 is xed as shown in Fig. 4, to the rear wall 5| of the carriage 3| by means of screws 42 and 43 and extends upwardly for the full length of the carriage 3| whereby to bisect the interior and to prevent the direct light rays of the light source 36 from striking the lens 39. The light reflecting prism 31 has two polished reflector surfaces 44 and 45 arranged at 1 an angle of 90 degrees with respect to each other for twice reecting a light beam generated by the light source 36. The prism 31 is affixed to the rear wall 5| of the carriage 3| by means of screws, such as shown at 52. The interior surfaces of the carriage 3|, and the surfaces of the light shield 40 are. blackened, whereby undesired light reflections are held. to a minimum. The rear surface of the prism 31 and a portion of the front surface of the prism 31 may also be rendered opaque for further restricting undesired light reiiections. Understandably, the light reflecting angular surfaces 44 and 45 and a discrete portion of the outer edges of the front surface of the prism will necessarily remain transparent.

Thus, light rays generated by the light source 36 will first strike the reflecting surface 45 which in turn will pass the light to the reective surface 44. The light beam reected from the surface 44 may then be projected through the elongated aperture 38 to the cylindrical lens 39. It will be obvious that generally the only light directly impinging upon the lens 39 will be that received from the light source 36 by means of the reflective surfaces 44 and 45 of the prism 31. The lensvv 39 is arranged upon the front exterior portion of the carriage 3| within a convex indentation 41. As shown in Fig. 2, the lens 39 is mounted by clamps 54 and 55 which are affixed to the side wall of the carriage 3|.

The aperture'38 is arranged along the apex of the convex indentation 41 and is in optical alignment'with the reflective surface 44 of the prism 31. Thelight beam emanating from sur face 44 isvthereby. projected through the aperture 38 to the cylindrical lens 39. The lens 33 is arranged immediately adjacent to the coating 21 of the background member 22, and the light beam projected and focused thereon will appear on the front of the tuning scale pane |1 in the form of an elongated luminous line which is employed as a dial pointer. The rear wall 5| of the carriage 3| is arranged with retaining edges 51 and 58 (Fig. 3) which frictionally engage with the side walls so that the rear wall is removable for the purpose of replacing or adjusting the light source 36.

The carriage 3| is moved in such a manner that as the resonant point of the receiver tuning elements is changed, the light beam |9 will indicate this change upon the scale face I1. A receiver cabinet 59 (Fig. 2) has been illustrated which is adapted to contain the chassis |0 and the tuning indicator and is provided with a relatively large aperture 64 to display the scale pane I1" to the operator. The tuning knob 28 is aillxed to a tuning shaft 68 (Fig. 2) which is connected to receiver tuning elements, not shown, contained within the chassis. A driving pulley 6| is arranged onthe tuning shaft 6|) whereby a driving cable 62 may be wound thereon and connected to a driving clamp 63 located atop the carriage 3| for moving the carriage. The cable 62 is arranged in the form of an endless belt (Fig. 1) and consists of a suitable dial cord. For the purpose 0f guiding the cable between the carriage 3| and the driving pulley 6|, there is ailixed to the upper and lower extremity of the supporting arm I4 a pair of rollers 66, 61 and there is similarly provided a like pair of rollers 68, 69 on the supporting arm l5. It will be evident that rotation of the tuning knob 28 will cause the shaft 69 and the pulley 6| to rotate and to impart a movement to the cable 62 where-f by the carriage 3| is caused to traverse the tracks 29 and 30.

Referring now to the operation of the tuning indicator I, assume that the receiver is energized, thereby causing energization of the edge lighting lamps 25, 26 and of the light source 36. The energization of the lamps 25 and 26 causes light rays to be projected to the edge of the transparent scale pane |1, which travel throughout the length of the scale pane |1 to strike and illuminate the indicia I8 arranged on its rear surface.

When light source 36 is energized, light rays impinge upon the reflective surface of the prism 31. These rays are conducted by the prism 31 to the opposite reflective surface 44 and are projected through the aperture 38 to the cylindrical lens 39. The translucent coating 21 of the background scale member 22 is generally impervious to light rays, excepting an intense beam of light. such as is projected and focused theme11. `by .the ylindreellens Si ,This light beam 'appears as a luminous line lliuo'n thef'front of the tuning scale pane I1." iheactualposi-2 tion of this beam of light' l'withrespect to the indicia i8 is correlated Withthe receiver. .tuning .apparatusand is indicativeof the resonancefpoint to which the receiver tuning elements .arev adjusted. It will be apparent, that rotation of the tuning knob 2t will cause the driving. cable 62 to move on its associated pulley members and to convey through the cable clamp 63 a likemovement to the. carriage 3|, so that the light beam IE will .similarly move to indicateon the tuning indicia I8 the particular radio frequency to which the receiver tuning. elements are adjusted,

It Will be evident that the. novel tuning-indicating mechanism employed Vin the present invention including a reflecting prism utilized'to transfer light rays from theirs'ource to the dial face permits the fabrication of a relatively shallow and compact carriage. The compactness thus attained provides for ease of installation of the movable carriage 3| behind a tuning scale and at the same time substantially reduces the depth of the receiver space required for the lateral movement of the carriage. IIt will be further evident that a considerable saving is effected by applying the indicia I8 to the tuning scale l1 in a relatively inexpensive and simple manner, but i.

the overall effect and the quality of the visual results achieved, equal the results obtained with a tuning scale having thereon the more expensive etched indicia.

Although the embodiment of the invention 2 It has also been found that the present in-` i vention is applicable to radio receivers having a plurality of tuning bands such as short Wave or frequency modulation bands in addition to the standard broadcast band. For such receivers, certain modifications of the present invention have been employed whereby the movable carriage is further compartmented and provided with a plurality of light sources to selectively project a separate indicating light beam representative of the selected tuning band. Thus, the selection of a particular Wave band provides for the energization of a rst light source Whereas the selection of a different band will extinguish the first light source and energize a second light source located in another compartment. The light beams are arranged to impinge upon a tuning scale which is indicative of the particular Wave band selected.

While there has been described what is at present considered the preferred embodiment of the invention, it will be obvious to those skilled in the art that various changes and modifications may be made therein without departing from the invention, and it is, therefore, aimed in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of the invention.

What is claimed is:

1. In a radio receiver, a tuning indicator comprising a first and a second transparent member arranged adjacent to each other, tuning indicia provided on the face of said rst member disposed adjacent to said second member, a substantially translucent coating on the outer face of said second member, a first source of light 6 arranges-tc project. light substantially. along one adjacent faces of. .said .members .l tol illuminate said indicia,ar.carriage, a .track disposed sub stantially parallel to .said members for .slidably mounting 'said carriage, means 'for moving said carriage along, said track, 4 a second source of light ou .said carriage Aarrangedin .close proximity to said members, a cylindrical lens mounted on said carriage adjacent to said coating, and means for projecting a beam oflight from. said second source onto said lens, thereby to provide a narrow luminous pointer. f

2- Ina radio receiver, a tuning indicator com# prising a .first and .a second transparent member arrangedadjacent. to each other, tuning `indicia provided on the face of said first member dis'- .posed adjacent to. `said second'member, a transf lucent coating on the outer face of said second member. a first source of light .arranged to prof ject light substantially alongL the face of said first member .adjacent to ,said lsecond member to illuminatesaid indicia, a carriage, a. track disposedsuhstantially parallel to said members for slidably mounting said carriage, means for moving said carriage along said track, a second source of light on said carriage arranged in close proximity to said members, an elongated cylindrical lens mounted on said carriage adjacent to said coating, and means for reiiecting a beam of light from said second source onto said lens, thereby to provide a narrow elongated luminous pointer.

3. In a radio receiver, a tuning indicator comprising a first and a second transparent plate arranged adjacent to each other, tuning indicia provided on the face of said first plate disposed adjacent to said second plate, a translucent coating on the outer face of said second plate, a iirst source of light arranged to project light substantially along the face of said first plate adjacent to said second plate to illuminate said indicia, a carriage, a track disposed substantially parallel to said plates for slidably mounting said carriage, means for moving said carriage along said track, a second source of light on said carriage arranged in close proximity to said plates. an elongated cylindrical lens mounted on said carriage adjacent to said coating, and a prism forv reecting a beam of light from said second source onto said lens, thereby to provide a narrow elongated luminous pointer.

4. In a radio receiver, a pointer mechanism for a `tuning indicator comprising a carriage, a track for slidably mounting said carriage, means for moving said carriage along said track, said carriage including a substantially light tight compartment, an aperture in said compartment, a light source in said compartment, a lens mounted on said carriage, a prism provided in said compartment for reflecting light from said source through said aperture on said lens, and a light shield disposed in said compartment between said source andsaid lens for substantially preventing direct light rays from said source from reaching said lens.

5. In a radio receiver, a pointer mechanism for a tuning indicator comprising a carriage, a track for slidably mounting said carriage, means for moving said carriage along said track, said carriage including aI substantially light tight compartment, an aperture in said compartment, a light source in said compartment, a cylindrical lens mounted on said carriage adjacent said aperture, a prism provided in said compartment for reflecting light from said source through saidaperture o'n` said 1e`n`s, arida' li'ghshleld disposed in said compartment `between said source and said lens for substantially preventing direct light rays from said source from reaching said lens. i h

6. In a radio receiver, a pointer mechanism for a tuning indicator comprising a carriage, a track for slidably mounting said carriage, means for moving said carriage along said track, said carriage including a substantially light tight compartment, an aperture in said compartment, a light source in said compartment, an elongated cylindrical lens mounted on said carriage adjacent to said aperture, a prism provided in said compartment for reflecting light from said source through said aperture on said lens, and a light shield disposed in said compartment between said source and said lens for substantiallypreventing direct light rays from said source from reaching said lens, said light source-being slidably mounted on said shield to vary the optical distance between said source and said lens.

The following references are of record in 8 REFERENCES CITED Number Name Date Shuman July 1, Dickey Dec. 31, Marcellus Jan. 10, Hopeld Feb. 28, Hansen et al. May 15, Brodton July 5, Hardesty Aug. 30, Colvin Oct. 11,4 Cooley Jan. 10, Strassenburg Sept. 19, Maris Mar. 12, Price Dec. 22, Gregory Jan. 23,

the 

